Source: Video and Images Created by Amanda Soderlind
Welcome to this lesson today on the Hypothalamus and Pituitary Gland. Today, we are going to be discussing the role of the hypothalamus and pituitary gland in the endocrine system. So the hypothalamus and pituitary gland interact in order to control activities of various body organs and to help regulate homeostasis of the body.
So the hypothalamus and pituitary gland produce various different types of hormones that regulate these body organs and help maintain homeostasis of the body. And the hypothalamus and pituitary gland can be found in the brain. So if we take a look at our diagram right here, up in this region here would be the hypothalamus. And then down here, we would have the pituitary gland.
And the pituitary gland is actually made up of two separate lobes, each of which produces different hormones. So the anterior lobe of the pituitary gland makes and releases hormones. And then the posterior lobe stores and releases hormones from the hypothalamus. So here we have the anterior lobe, and here we have the posterior lobe.
So we have the hypothalamus again here, which is then working closely with the pituitary gland, which is composed of the anterior and posterior lobes. So we're going to start by taking a look at what happens in the posterior lobe of the pituitary gland. So basically within the hypothalamus up here, we have neurons. So you can see all of our neurons right here in green, and these neurons synthesize antidiuretic hormone and oxytocin.
So then basically what happens is these neurons have synthesized these two hormones, and these hormones will move down the axons of the neurons and they'll build up in our axon endings down here, which are located in the posterior lobe. So they're being produced up here in the hypothalamus, moving down the axons, and being stored in the axon endings located in the posterior lobe. So then when an action potential triggers a hormone release, the hormones will enter capillaries and then they'll be able to travel through the bloodstream to whatever their target cell is.
So as I mentioned, oxytocin is one of the hormones that's produced in the hypothalamus and then is stored in these axon endings of the neurons in the posterior lobe. So oxytocin plays a couple of different roles. One of its target cells is mammary glands. And in these mammary glands, it causes milk to move into the ducts.
And then it also acts on muscles in the uterus wall that cause contractions during childbirth. So oxytocin is this hormone basically that's active in women who are about to give birth or who have given birth. So It acts on those mammary glands in order to move milk into ducts, or to help with contractions during childbirth.
So oxytocin is one of them, and then antidiuretic hormone, also abbreviated ADH, is another hormone that's again produced in the hypothalamus and then is stored in the axon endings in this posterior lobe. An antidiuretic hormone plays a role in kidney nephrons, and basically what it does is it causes water to be conserved in those kidney nephrons. So oxytocin and ADH are stored in the posterior lobe of the pituitary gland.
If we take a look at our anterior lobe, the way that this works is a little bit different. So we have these neurons up here in the hypothalamus that will secrete certain hormones. And then, those hormones will be picked up by capillaries at the base of the hypothalamus. So we have the hormones secreted here, moving down the axons. And then at the base of the hypothalamus, those hormones will be picked up by capillaries and they'll be delivered to a capillary bed in the anterior lobe here.
So then molecules of those hormones will act on endocrine cells in the anterior lobe. And then, hormones from the anterior lobe cells will enter blood vessels and then will be carried through the bloodstream in that manner. So these here are the hormones that are released by the anterior lobe of the pituitary gland.
So we're going to start by talking about growth hormone, which is sometimes abbreviated GH. So growth hormone is a hormone that regulates a person's growth. That is secreted by this anterior lobe.
Prolactin, abbreviated PRL, basically prolactin plays a role in milk production in mammary glands. Luteinizing hormone, LH, plays a role in the reproductive system. It also helps with the secretion of other hormones and it's found mostly in the ovaries and testes, so it's a part of the reproductive system.
Follicle stimulating hormone, FSH, is another hormone that plays a role in the reproductive system, so it's found in ovaries and testes, and it plays a role in gamete formation. Thyroid stimulating hormone, or TSH, is a hormone that controls the release of thyroid hormone. And then our last one here is adrenocorticotropic, which is abbreviated ACTH, and this hormone stimulates the release of cortisol from the adrenal glands. So these are all the various different hormones that are secreted by the anterior lobe. So this lesson has been an overview on the role of the hypothalamus and pituitary gland in the endocrine system.
Also called the adenohypophysis, the anterior lobe of the pituitary gland started developing in the nasopharynx and migrated up into the skull to join with the posterior lobe of the pituitary gland. Since the anterior pituitary didn’t originate in the brain there are no direct neural connections to it. The anterior pituitary gland secretes six hormones: growth hormone (GH), adrenocorticotropic hormone (ACTH), thyroid stimulating hormone (TSH), prolactin, luteinizing hormone (LH), and follicle stimulating hormone (FSH).
A part of the forebrain that works closely with the pituitary gland to monitor the body's organs and their functioning.
Called the “master gland” because of its effects on other glands; endocrine hormones increase activity/secretion of many major glands of the endocrine system.
Also called the neurohypophysis, the posterior lobe of the pituitary gland developed from brain tissue during embryonic development and therefore is directly innervated by the hypothalamus. The two hormones the posterior pituitary secretes are anitdiuretic hormone (ADH) and oxytocin.